1. Field of the Invention
The present invention relates to a novel sulfonyloxime compound suitable for use as a radiation sensitive acid generator and thermosensitive acid generator constituent of a radiation sensitive resin composition used as a chemically amplified resist in which ultrafine processing is performed using any of a variety of different types of radiation including KrF excimer lasers, ArF excimer lasers, F2 excimer lasers, (ultra) far ultraviolet radiation such as EUV, X rays such as synchrotron radiation, and charged particle beams such as electron beams, and also relates to a radiation sensitive acid generator, a chemically amplified positive type radiation sensitive resin composition and a chemically amplified negative type radiation sensitive resin composition using such a sulfonyloxime compound.
2. Description of the Related Art
In the area of ultrafine processing, typified by the manufacture of integrated circuit elements, lithography techniques which enable ultrafine processing to be performed at a level of less than 0.20 xcexcm have become necessary in order to achieve ever greater levels of integration.
However, in conventional lithography production processes, near ultraviolet radiation such as an i line is typically used as the radiation, and it has been reported that when this type of near ultraviolet radiation is used, ultrafine processing at the subquarter micron level is extremely difficult.
Consequently, in order to make ultrafine processing possible at levels of less than 0.20 xcexcm, the use of radiation of shorter wavelengths is being investigated. Examples of radiation with a shorter wavelength include far ultraviolet radiation typified by an excimer laser or the line spectrum of a mercury light, X rays, and electron beams and the like, and of these, KrF excimer lasers (wavelength 248 nm), ArF excimer lasers (wavelength 193 nm), F2 excimer lasers (wavelength 157 nm), EUV (wavelength 13 nm or the like) and electron beams and the like are attracting particular interest.
Examples of radiation sensitive resin compositions which are suitable for use with this type of short wavelength radiation include compositions which utilize the chemical amplification effect between a constituent with an acid dissociable functional group, and a radiation sensitive acid generator which generates an acid on irradiation with the radiation (hereafter described as xe2x80x9cexposurexe2x80x9d), and many of these types of compositions (hereafter described as chemically amplified radiation sensitive compositions) have been reported.
Specific examples of chemically amplified radiation sensitive compositions include the compositions disclosed in Japanese Post-Examination publication (kokoku) No. 2-27660 (JP2-27660B), incorporating a polymer with a t-butyl ester group of a carboxylic acid or a t-butyl carbonate group of a phenol, and a radiation sensitive acid generator. When these compositions are exposed, the acid generated by the exposure causes a dissociation of the t-butyl ester groups or the t-butyl carbonate groups in the polymer, forming acidic carboxyl groups or phenolic hydroxyl groups within the polymer, and as a result, the exposed regions of the resist become readily soluble in the alkali developing solution.
However, when the design dimensions of a device fall below the subhalf micron level, requiring even more precise control of the line width, high resolution alone is insufficient, and a superior level of smoothness of the film surface following formation of the resist pattern is now also becoming an important factor. If a chemically amplified resist with an inferior level of surface smoothness is used, then when the resist pattern is transferred to a substrate using a process such as etching, the irregularities in the film surface (so-called nano edge roughness) are also transferred to the substrate, causing a deterioration in the precision of the dimensions, and ultimately a deterioration in the electrical characteristics of the device (for example, J. Photopolym. Sci. Tech. p571, 1988; Proc. SPIE Vol. 3333, p313; Proc. SPIE Vol. 3333, p634; J. Vac. Sci. Technol. B16(1), 1998, p69).
Taking the above circumstances into consideration, an object of the present invention is to provide a sulfonyloxime compound which displays superior heat stability and storage stability, and which is capable of generating a resist pattern with superior smoothness of the surface and side walls thereof, for use as an acid generator sensitive to activated radiation such as KrF excimer lasers, ArF excimer lasers or F2 excimer lasers, far ultraviolet radiation typified by EUV, or electron beams and the like, as well as to provide a radiation sensitive acid generator, a positive type radiation sensitive resin composition and a negative type radiation sensitive resin composition using such a sulfonyloxime compound.
The above object was able to be achieved by using a specific sulfonyloxime compound, described below, as a constituent of a radiation sensitive acid generator.
In other words, a first aspect of the present invention provides a sulfonyloxime compound represented by a general formula (1) shown below, 
wherein, R1 represents a hydrogen atom, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group, R2 represents a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group, X represents a halogen atom, Y represents xe2x80x94R3, a xe2x80x94COxe2x80x94R3 group, xe2x80x94COOxe2x80x94R3 group, xe2x80x94CONR3R4 group, xe2x80x94Sxe2x80x94R3 group, xe2x80x94SOxe2x80x94R3 group, xe2x80x94SO2xe2x80x94R3 group, a xe2x80x94CN group or a xe2x80x94NO2 group, and R3 and R4 within the Y group each represent, independently, a hydrogen atom, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, substituted or unsubstituted aryl group, or substituted or unsubstituted heteroaryl group, although any two of R1, R2 and R3 may also be bonded together to form a cyclic structure having the formula (2-1), formula (2-2) or formula (2-3) below, 
wherein, Yxe2x80x3 represents a single bond or a bivalent group formed when the R3 group is removed from the aforementioned Y group, and furthermore dimers represented by the formula (3-1), formula (3-2) or formula (3-3) shown below, in which one of the groups R1, R2 or Y functions as a linkage group R1xe2x80x2, R2xe2x80x2, or Yxe2x80x2 respectively, are also possible. 
wherein, R1xe2x80x2, R2xe2x80x2 and Yxe2x80x2 each represent a bivalent group formed by bonding together residues generated by dissociating one atom or group from two separate R1, R2 or Y groups belonging to separate molecules.
A second aspect of the present invention provides a radiation sensitive acid generator comprising an aforementioned sulfonyloxime compound.
A third aspect of the present invention provides a chemically amplified positive type radiation sensitive resin composition comprising (A) a radiation sensitive acid generator incorporating an aforementioned sulfonyloxime compound, and (B) an alkali insoluble or alkali sparingly soluble resin protected with an acid dissociable group, which becomes alkali-soluble on dissociation of the acid dissociable group.
A fourth aspect of the present invention provides a chemically amplified negative type radiation sensitive resin composition comprising (A) a radiation sensitive acid generator incorporating an aforementioned sulfonyloxime compound, (C) an alkali-soluble resin, and (D) a compound which is capable of cross-linking with the alkali-soluble resin in the presence of an acid.